The subject of the present invention is a dispenser of liquid or pasty product that can be used especially in cosmetics.
Dispensers are already known that comprise a reservoir containing liquid or pasty product to be dispensed and a variable-volume chamber formed, for example, by a cylinder and a piston. The reservoir is connected by a first valve to the variable-volume chamber, which opens to the outside of the dispenser through a second valve. By causing the volume of the variable-volume chamber to vary, with the aid of a push-button, a pumping action is exerted causing the liquid or pasty product to pass from the reservoir into the variable-volume chamber and then to the outside of the dispenser.
Such known devices have the drawback that if, for any reason, an excess pressure is produced in the receptacle, the liquid or pasty product flows out of the dispenser, opening the two valves it encounters on its way. This adversely affects the seal of the device.
In addition to this, when such known devices are used with a rigid non-contractable reservoir, it is necessary to leave an opening for the passage of air, which has to progressively take the place of the product extracted from the receptacle by the dispenser.
This opening is also a source of leakage for the device.